This invention relates to gas-coolant nuclear breeder reactors. Such a reactor is totally enclosed by a steel containment vessel. The reactor includes a core enclosed by a pressure vessel, the core including fuel elements each comprising a bundle of fuel rods which, if operated at excessive temperatures, may melt and fall. Therefore, a melt core intercept basin is positioned beneath the core. In the event the melted core falls into this basin, the core's heat must be dissipated rapidly because if uncontrolled, there may be a excessive pressure increase inside of the steel containment vessel which might damage the integrity of the latter. With adequate heat dissipation, such a pressure rise may be suppressed to a safe level.
The prior art has suggested a basin inside of the pressure vessel directly beneath the core and which is provided with indirect cooling means in the form of water pipes. The idea is to dissipate the heat, presumably through evaporation of the water forming steam, but the prior art has made no provision for handling the resulting steam in a practical manner. A concept of this kind is suggested by the German Offenlegungsschrift 2,035,089.